Endoscopic management of malignant hilar obstruction

Inoperable high-grade malignant hilar biliary obstruction (MHBO) has long been a challenging issue for the endoscopist. In recent years, biliary surgeons have tended to operate aggresively on even the most advanced hilar tumors, making endoscopic palliation a target for increasingly advanced lesions. In addition, recent advances in anticancer therapy have resulted in an increasing number of patients with unresectable hilar tumors surviving significantly longer than the patency duration of self-expandable metal stents (SEMS), so a strategic approach to biliary drainage is essential.
The most crucial aspect of endoscopic treatment in advanced MHBO is compelling drainage and minimizing complications during the treatment process, including the first drainage procedure and planned stent exchange, to avoid delay and interruption of chemotherapy. The choice of endoscopic versus percutaneous treatment for advanced MHBO is hotly debated. In contrast to the distal malignant biliary obstruction, there is no one-size-fits-all practice guideline in MHBO due to various clinical situations. In these situations, the priority of treatment is selecting a procedure that benefits the patient and the procedure's safety rather than the operator's satisfaction.
The basic principle of biliary drainage is that the drainage plan should be based on the anatomic findings of biliary obstruction before the drainage procedure. Drainage of over 50% of the viable liver parenchyma results in a lower incidence of cholangitis and survival benefit. We should avoid the drainage of sectoral ducts associated with segments of atrophic liver parenchyma. A backup system should be in place to immediately attempt alternative drainage strategies when conventional ERCP is not possible or when adequate drainage of injected contrast media is not possible.
SEMS is preferred to plastic stent due to longer stent patency in MBO palliation. However, in MHBO, bare SEMS shows recurrent biliary obstruction due to tumor ingrowth and leads to difficult re-intervention and consequent short-term and frequent cholangitis. Therefore, endoscopic intervention with PS is recommended as an initial approach.
PTBD drains most biliary lesions that failed in ERCP. However, long-term indwelling percutaneous biliary drains can negatively impact the patient's quality of life because of pain, the need for routine site care, and frequent catheter exchanges. EUS-hepaticogastrostomy (EUS-HGS) has been developed and applied to treat MHBO. EUS intervention will be expected to replace many cases of PTBD in advanced MHBO patients. Comparison between PTBD and EUS-HGS in this field will be the subject of a lengthy discussion.